I know, so why do they need to speak "perfect" English.
Good fluent English is more than sufficient, especially if they are only going to use it to speak to people travelling or doing business in China.
Not many Chinese have the luxury of going abroad to learn!
"Once a person has passed the intermediate stage of language learning they can generally learn best by simply spending time in the country where the language is spoken, a teacher is a luxury and not a necessity."
f you want the best example to learn from when learning to speak(phonetics) a language, then it is best to get it from the source (that is if you can).
Many people cannot, and if you have a good non-native speaker I doubt it will make much difference until you are at an advanced level.
Once a person has passed the intermediate stage of language learning they can generally learn best by simply spending time in the country where the language is spoken, a teacher is a luxury and not a necessity.
A good non-native teacher is better than a native speaker who just calls him/herself a teacher in order to work overseas.